How to improve surface finish on a machined aluminum/steel part

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Hello all,

My name is Andrew Germain and I am a student/co-op mechanical engineer who attends Kettering University, formerly General Motors Institute of Technology. I have been given the task of finding ways to improve surface finish on a machined aluminum or steel part. However, the guidelines are that the improvement comes from within the machining processes we use, and therefore additions of a grinding operation, or the addition of any other operation is less than ideal.

My question is this, is there anyway to improve surface finish by changing the machines cutting head speed, depth of cut, or any other parameter? I have found on the Internet that the addition of a coolant to a preexisting operation can be beneficial, but have not found significant sources to back up this claim.

Thank you all for your help, and thanks to everyone who's response to other topics has already proven beneficial.

Andrew Gregory Germain
Co-op engineer/student - Montague, Michigan, U.S.A.

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Optimal machining parameters depend upon the particular alloy and heat treatment condition. Your school may already have a machining database with tool geometry, speed, depth of roughing and final cuts, etc. Appropriate cutting fluids can improve machining finish by removing heat and acting as lubricant. This also improves productivity and tooling life. See Machinery's Handbook or Metals Handbook Vol. 16 Machining (1989). A Machining Data Handbook (3rd edn., 2 vols., 1980) was published by the DoD-funded Machinability Data Center (Metcut Research in Cincinnati). Much info significantly pre-dates the Internet, e.g., Machining Aluminum Alloys (Reynolds Metals Co., 1952), Machining Kaiser Aluminum (1955), or Aluminum Vol. III, Fabrication and Finishing (1967). There are also newer, basic and advanced CNC Machining books.

The National Center for Manufacturing Sciences (http://www.ncms.org) may be of help (GM is a partner). A recent project 'DEVELOPMENT AND EVALUATION OF NEAR-DRY MACHINE TOOLS FOR THE PRODUCTION OF ALUMINUM COMPONENTS' may be of interest.

Suppliers of machining fluids, such as Chemetall Oakite, Henkel, MacDermid, etc., may have product bulletins and other info.

Ken Vlach
- Goleta, California